ARCTIC CAT F7 snapped crank at primary

captnviper

captnviper

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Okay let me start by saying this is not my machine I am however capable of using a computer. Anyway this machine when new went through numerous belts due to the deflection wandering and the belts would explode from being to tight. This is by the way DD sled so the deflection nut was replaced. the offfset way also way off from the factory we corrected the with alignment tool. so he went thru many belts but we thought it was finally dialed in. Then yesterday just pulling away from a stop at about 5k he hears the engine over rev thinks its yet another belt. Open the hood and theres the primary laying there with the crank snapped clean off. We had been adjusting the spring in the secondary trying to get a little more backshift. Anyways anyone else ever have or hear of this happening? Was there a recall he missed? what would cause this?

P.S. If this should be in a different topic area please let me know. And even though this is acrtic cat he is my best riding bud! So any help would be apprieciated. :o|
 

Ouch!!! That is too bad for your bud.

I know very little about that sled or engine, but 2 possible causes come to mind . . . Either the crank was stressed beyond spec in the belt events or some other event that occurred, or the crank had a defect in it that showed up after a good deal of stress occurred. (kinda stating the obvious, sorry) - I find it hard to believe that blowing belts itself overstressed the crank, but a related event may have.

I hope it is a warranty item, but would check with another forum like arcticchat or hcs to see if it is a common issue. I do understand (having never done that engine) that they are easy to rebuild, and cranks are readily available.

I wonder if we should move this to the general or lounge area.
 
When we looked closely at the broke part looked like sh**ty casting. Oh I did post at arctic chat. I posted here also cause seems to be alot of knowledge on this site.
 
Last edited:
YAMMIEGOD3:16 said:
ALL THEM BELTS BLOWING ON THAT SLED CAUSED THIS. CRANKSHAFT TAKES TERRIBLE BEATING WHEN YA BLOW BELTS. 3:16 (yammie tony)
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This is what I thought when he first started going thru belts. I thought he should have said something to his dealer when he was having all the trouble. He even had the secondary replaced under warranty cause it got wrecked one time when the deflection tightened way up.
 
THAT IS A VIOLENT EXPLOSION EVERYTIME A BELT BLOWS, AND NOT ONLY THAT MOTOR FREE REVS. MY GUESS CRANK WAS BENT AND JUST SNAPED AT WEAK SPOT. 3:16 (yammie tony)
 
YAMMIEGOD3:16 said:
ALL THEM BELTS BLOWING ON THAT SLED CAUSED THIS. CRANKSHAFT TAKES TERRIBLE BEATING WHEN YA BLOW BELTS. 3:16 (yammie tony)
Click to expand...


BINGO!!!!
 
Yeah what a crappy deal cause it did all this new. We got the belt blowing issue fixed 2 years ago maybe 3 but the damage was done. I still have my orignal belt as my spare. Thanks for the replies I posted on arctic chat first still no replies.
 
mrviper700 said:
BINGO!!!!
Click to expand...

Its amazing how much stress blowing a belt will cause an engine. My brother-in-law blew a belt on his SRX and below is what happened.

1. All but 2 springs came off the exhaust
2. Recoil shattered
3. Clutch became out of balance. We had to pull clutch off and re-torque.

Sorry to hear of his trouble.
 
WHAT CAUSES THIS ? FROM WHAT I HAVE SEEN.
1. PRETTY SIMPLE WRONG BELT
2. OFFSET WRONG
3. CENTER/ CENTER WRONG
4. EXCESSIVE HEAT
5. BROKE,IN MOTOR MOUNT OR WEAK MOUNT.
6. ANOTHER PROBLEM THAT SOMETIMES OVERLOOKED, IF THE MACHINE WAS IN A ACCIDENT OR ROLLED, FRAME OR CHASSIS SLIGHTLY TWEAKED OR BENT. 3:16 (yammie tony)
 
Maybe you haven't heard anything on the AC sight because of your "captnviper" name!

...LOL!...

I agree that damaged was most likely done to that crank with it blowing so many belts. If the runout was excessive and or the clutch out of balance it definately could cause this.
Some sleds like the 650 polaris tripples would break crankshafts at the crankpins if they were run at 8800 rpm due to a hamonic frequency issue. I have not heard of F7s having crank breakage issues at least not in our kneck of the woods.
I have only seen two sleds throw a clutch like that...a 1972 340 TNT and a 1970 340 Moto Ski. Pretty spectacular when it occurs, especially on the old exsposed engine sleds!
 
YAMMIEGOD3:16 said:
WHAT CAUSES THIS ? FROM WHAT I HAVE SEEN.
1. PRETTY SIMPLE WRONG BELT
2. OFFSET WRONG
3. CENTER/ CENTER WRONG
4. EXCESSIVE HEAT
5. BROKE,IN MOTOR MOUNT OR WEAK MOUNT.
6. ANOTHER PROBLEM THAT SOMETIMES OVERLOOKED, IF THE MACHINE WAS IN A ACCIDENT OR ROLLED, FRAME OR CHASSIS SLIGHTLY TWEAKED OR BENT. 3:16 (yammie tony)
Click to expand...
Yeah they recalled a the deflection adjuster nut on these sleds. Also the offset was way off when he checked it. But I think the damage was already done by then.
 
and this Cat came out of the factory like that!!Where was the quality control ,must of been made on a Friday....before a long weekend..lol.Someone didn't do their job right at the plant,your buddy just happened to be the one who bought this sled.To bad you can't dig into it and find out from Artic Cat if there some similar incidents around the time your sled was manufactured.If you could find out like maybe a number of sleds from that date all had similar issues..maybe your bud could go after AC for the damage..but I imagine AC would tend to hide that info so no one finds out.Same as BRP didn't care about driveshafts blowing apart years back,as long as there was a small percentage of customers calling in..they would not do a recall and see what happens after 1 year has passed.They use a percentage number as normal amount that wouldn't warrant a free fix.
Maybe give AC a call with your sin # and ask if there any recalls for that model or updates that may have been missed.
 
bluemonster1 said:
and this Cat came out of the factory like that!!Where was the quality control ,must of been made on a Friday....before a long weekend..lol.Someone didn't do their job right at the plant,your buddy just happened to be the one who bought this sled.To bad you can't dig into it and find out from Artic Cat if there some similar incidents around the time your sled was manufactured.If you could find out like maybe a number of sleds from that date all had similar issues..maybe your bud could go after AC for the damage..but I imagine AC would tend to hide that info so no one finds out.Same as BRP didn't care about driveshafts blowing apart years back,as long as there was a small percentage of customers calling in..they would not do a recall and see what happens after 1 year has passed.They use a percentage number as normal amount that wouldn't warrant a free fix.
Maybe give AC a call with your sin # and ask if there any recalls for that model or updates that may have been missed.
Click to expand...
Yeah needless to say he is way mad wants to go after them but would b very diffucult Im sure.
 
yea, my roomate has a 03 f7. has gone through 2 cranks and about 5 top ends. its something that happens i guess with those motors. they just have so much power, they tend not to hold up.
 
THATS WHY THEY CALL THEM FIRE SCRAP. THOSE SLEDS ARE GOOD FOR ONE THING, RACING!! THATS IT. OTHERWISE THEY ARE JUNK. 3:16 (yammie tony)
 
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